// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package k12

import (
    "crypto/subtle"
    "encoding/binary"
    "unsafe"

    "golang.org/x/sys/cpu"
)

// xorIn xors the bytes in buf into the state.
func xorIn(d *state, buf []byte) {
    if cpu.IsBigEndian {
        for i := 0; len(buf) >= 8; i++ {
            a := binary.LittleEndian.Uint64(buf)
            d.a[i] ^= a
            buf = buf[8:]
        }
    } else {
        ab := (*[25 * 64 / 8]byte)(unsafe.Pointer(&d.a))
        subtle.XORBytes(ab[:], ab[:], buf)
    }
}

// copyOut copies uint64s to a byte buffer.
func copyOut(d *state, b []byte) {
    if cpu.IsBigEndian {
        for i := 0; len(b) >= 8; i++ {
            binary.LittleEndian.PutUint64(b, d.a[i])
            b = b[8:]
        }
    } else {
        ab := (*[25 * 64 / 8]byte)(unsafe.Pointer(&d.a))
        copy(b, ab[:])
    }
}
